According to an article in The Telegraph, research performed by a team from the University of Western Australia and the University of Queensland has revealed that the 17 species of sharks (which included bull sharks and tiger sharks) involved in the study are effectively color blind. Examination of the retinas of the 17 species indicated that only one type of cone was present, which would allow the sharks to only be able to discern shades of light and dark. In comparison, humans have three types of cones which correspond to the ability to distinguish red, green, and blue.
Based on the research, The Telegraph article states that wearing light colored swimwear would reduce contrast with the water, implying that the reduced contrast might result in a decreased chance that a shark would attack. The article also claims that the study “backs up” shark attack statistics which indicate that a “vast majority of attacks happen to divers and surfers wearing black wetsuits.” Unfortunately, the article fails to mention that a vast majority of wetsuits are black, so the probability of a surfer or diver wearing a wetsuit that is black is going to be pretty high regardless of whether they are attacked by a shark or not.
The article goes on to discuss how this finding may be applied to surfing, swimming, and diving apparel. Nathan Hart, the lead author of the study, contends that “brightness contrast is more important for detecting and identifying objects” for the color blind sharks. Additionally, Hart is hopeful this research might be applied to the design of longline fishing hooks to make them less likely to attract sharks and reduce the mortality rates of sharks as a result of longlines.